The invention is based on a vehicle heater of the type generally known from DE 10 2011 112 196 A1.
Vehicle heaters in which heating elements are arranged in chambers of pipes have the advantage that the heating elements are well protected against ambient influences.
Higher heating powers are increasingly demanded by vehicle manufacturers, and increasingly smaller installation spaces are provided for vehicle heaters.
The present invention provides a way in which these demands can be met with a cost-effective vehicle heater.
Higher heating powers require a correspondingly larger space for ceramic heating elements, which are arranged in the chambers of pipes. A problem here is that the chambers cannot be enlarged arbitrarily, since an increasingly poorer thermal coupling of the heating elements to the pipe surrounding the heating elements occurs in larger chambers. For good thermal coupling, the pipes of vehicle heaters have to be compressed so that good thermal contact is provided between an upper side and underside of the chambers and the heating elements arranged therebetween. The wider the chambers, the greater is the risk that sufficient thermal contact will no longer be attainable in spite of compression.
With known vehicle heaters, an increased number of chambers is associated with the disadvantage of a correspondingly greater number of component parts and a correspondingly greater contacting effort. This disadvantage is overcome with a vehicle heater according to this disclosure in that the heating elements are contacted by contact plates having a slit, in which an intermediate wall separating two chambers of a pipe is arranged. With a vehicle heater according to this disclosure, a contact plate can thus contact heating elements in a plurality of chambers. The number of required component parts is thus advantageously reduced. A printed circuit board that carries a control circuit of the vehicle heater thus requires fewer contact points to contact plates, since a correspondingly smaller number of contact plates is sufficient. The contact plates may have, at one end, an extension that plugs into the printed circuit board.
The intermediate wall between two chambers of a pipe can be hollow, e.g., as is the case with the pipe of a vehicle heater illustrated in FIG. 4 of DE 10 2011 112 196 A1. The intermediate wall, however, preferably is not hollow, but solid.
As already mentioned, the thermal contact between a pipe and the heating elements arranged therein can be considerably improved by compressing the pipe. The direction of force during the compression is oriented perpendicularly to the plane of the contact plate or the contact plates. It is therefore advantageous for the intermediate wall to extend from the upper side to the underside of the chambers separated thereby. Here, the upper side and the underside of a chamber are to be understood to be the two sides that face the front side and rear side respectively of a contact plate arranged in the chamber. The front side of a contact plate is the side via which the contact plate contacts heating elements. In the case of a rectangular chamber, the upper side and underside thus extend parallel to the front side and the rear side of a contact plate.
In an advantageous refinement of this disclosure, a plurality of pipes, each of which has at least two chambers, are arranged side by side. Due to the use of a plurality of pipes, each of which has a plurality of chambers, a greater heating power can be achieved in a given volume. The pipes can be arranged at a distance from one another. Heat produced by the heating elements can then be transferred very efficiently to air flowing between the pipes. The pipes can be interconnected by heat transfer members, for example fins. Heat transfer elements are not absolutely necessary. Adjacent pipes preferably face one another via their upper sides and undersides. The flow resistance of the pipes can thus be minimized advantageously.
In accordance with an advantageous refinement of this disclosure, the pipes are flat pipes. Flat pipes have broad upper sides and undersides, which are interconnected via narrow sides. The intermediate wall or each intermediate wall extends from the upper side to the underside of the pipes. The flat pipes can have exactly two chambers, in which heating elements are arranged. If flat pipes having more than two chambers are used, the chambers are preferably arranged in a row beside one another.
If the pipes are used to connect the heating elements to earth, a single contact plate in a chamber is sufficient. In particular, with greater electric voltages, it is advantageous to arrange the heating elements between two contact plates, each of which is insulated with respect to the pipes.